Abstract:

In this paper we compare water and ozone as oxidants in the Al2O3 ALD reaction in terms of surface passivation quality. The experiments show that O3 produces a high negative charge density up to 7-1012 cm−2 even in as-deposited film, which is different from water based Al2O3 that requires a separate annealing step to activate the negative charge. In general, the ozone process produces lower interface defect density (Dit) and higher negative charge density, which contributes to the higher lifetime value than corresponding water process. Most importantly, ozone-based Al2O3 shows much better firing stability than water-based Al2O3. Ozone concentration is also shown to play a role in the surface passivation quality. Finally, we found out that inserting a water pulse after the ozone pulse can lower the Dit further resulting in even higher lifetime.